Modern key telephone systems are being developed which operate under program control to provide an ever increasing variety of calling features. Typically, these programs are contained in read-only memories (ROMs) located on memory cards. To minimize program changes required to accommodate changes to system hardware or operating features, the system memory can be arranged into hardware-dependent (personality) and hardware-independent (feature) modules. Thus, for example, when a change is made in the operating feature only the feature module need be changed. To facilitate changes to operating features, interchangeable memory cards or cartridges can be utilized.
For example, in the copending U.S. patent application, Ser. No. 445,982, filed on Dec. 1, 1982, by Bennett et al, now U.S. Pat. No. 4,506,346 a programmable cartridge based telephone communication system is disclosed where a variety of user interchangeable cartridges can be plugged into the system to program a variety of operating features. Since the addresses of existing feature programs may vary from cartridge to cartridge or since a new program may be added on subsequent cartridges, programs resident on the personality module of the system require a method of locating programs resident on any of these feature cartridges and vice-versa.